A vehicle is provided with an engine and components driven by the engine. An alternator is one of the components driven by the engine. According as electricity generated by the alternator is increased, the engine torque which is consumed by the alternator is also increased, so that fuel consumption of the engine is increased.
JP-2004-260908A (US-2004/0164616A1) shows a system in which an electricity generation cost is calculated to intensively generate electricity in a timing in which electricity generation cost is low so that the fuel consumption is reduced.
When the alternator intensively generates electricity in a short period, the engine torque to drive the alternator is rapidly increased. Since the engine torque is controlled based on a throttle position, a fuel injection quantity, and a fuel injection timing, a responsiveness delay of the engine control arises, so that the engine torque is belatedly increased. Consequently, the torque for driving the vehicle is temporarily dropped off and the engine speed is temporarily dropped off. Thus, the drivability is deteriorated and a required electricity may be hardly obtained.
The above problem may be arisen with respect to a compressor for air-conditioner, which is one of components. When the compressor is started, the engine speed may be temporarily dropped off.